// display the dates of all holidays in given year.
listHolidays(year)
    date = date of first day of a given year
    while (date is before the first day of year+1)
    {
        if (date is a holiday)
            write (date,"is a holiday")
        date = date of next day
    }

// Return the date of the first day of a given year
  +getFirstDay(year: int): Date
// Return true if this date is before the given date; otherwise returns false
  +isBefore(otherdate: Date): boolean
// Return true if this date is holiday; otherwise return false
  +isHoliday(): boolean
// Return the date of the day after this day.
  +getNextDay(): Date


// Display the dates of all holidays in a given year.
listHolidays(year: int): void
    date = getFirstDay(year)
    while (date.isBefore(getFirstDay(year+1)))
    {
        if (date.isHolidDay())
            write (date,"is a Holiday")
        date = date.getNextDay()
    }
    
        